Mast Cell Tumours in Dogs: Welfare and Treatment Guide
Disease Overview
Mast cell tumours (MCTs) are malignant neoplasms arising from mast cells in the skin and subcutaneous tissue. They account for 16-21% of canine skin tumours. They vary enormously in biological behaviour from low-grade tumours that can be cured by surgery to high-grade tumours with rapid metastasis and poor prognosis. Boxers, Bulldogs, Boston Terriers, Labrador Retrievers, and Golden Retrievers are predisposed breeds. MCTs can appear as any type of skin mass.
Grading and Prognosis
Histopathological grading guides prognosis and treatment. The Patnaik system uses grades I-III; the Kiupel two-tier system (low versus high grade) has strong prognostic value. High-grade tumours carry median survival times of weeks to months; low-grade tumours treated with complete excision can have excellent long-term prognosis. Ki67 index (cell proliferation marker) and c-Kit mutation status further refine prognosis and treatment selection.
Welfare Consequences
MCTs release histamine and other mediators causing local effects (erythema, swelling, 'waxing and waning' appearance) and systemic effects (vomiting, duodenal ulceration). Manipulation of tumours can trigger degranulation and anaphylaxis. Dogs with systemic mastocytosis experience chronic discomfort. Metastatic disease causes lymph node enlargement, splenomegaly, and systemic illness. Treatment side effects (surgery, chemotherapy) add to welfare burden.
Treatment Options
Wide surgical excision with adequate margins is the primary treatment. Incomplete excision requires re-excision or radiation therapy. Toceranib (Palladia) and masitinib target c-Kit mutations and are effective in certain subtypes. Prednisolone provides tumour debulking and reduces degranulation. Vinblastine and lomustine are conventional chemotherapy options for high-grade or metastatic disease. H1 and H2 antihistamines reduce gastrointestinal side effects.
Long-term Welfare Monitoring
Regular post-treatment monitoring includes physical examination, regional lymph node assessment, and abdominal ultrasound. Early detection of recurrence or metastasis allows timely intervention. Owners should be educated to monitor for new masses and changes in existing ones. Quality of life scoring helps guide decisions when disease progresses. Dogs with well-controlled low-grade MCTs can maintain excellent welfare for years.